Count substring in string

Question

With the comments on the same line as the code, it refers to. e.g

NumBob = 0
s = 'sexbobombob'
i = range(len(s)+1) #Generates a list from 0 to the length of s
u = 0 # This would be the variable storing each value of the list
for ans in i: # this allows me to extract each value of i
 if ans > 0: # Completely arbitrary. i just used any condition that allows me to pick up all values in the list.
 u = ans
 x = s[u:u+3] #By using indexing to pick u, u+1, and u +2 i can pick up 3 letters at a time
 if "bob" in x: # Checking if the term i picked up is a Bob
 numBob += 1 # increasing the Bob count
print "Number of times bob occurs is:" + str(numBob) # Printing the number of Bobs

With the comments beneath the line of code, it refers to. e.g

numBob = 0
s = 'sexbobombob'
i = range(len(s)+1)
#Generates a list from 0 to the length of s
u = 0
# This would be the variable storing each value of the list
for ans in i:
 # this allows me to extract each value of i
 if ans > 0:
 # Completely arbitrary. i just used any condition that allows me to pick up all values in the list.
 u = ans
 x = s[u:u+3]
 #By using indexing to pick u, u+1, and u +2 i can pick up 3 letters at a time
 if "bob" in x:
 # Checking if the term i picked up is a Bob
 numBob += 1
 # increasing the Bob count
print "Number of times bob occurs is:" + str(numBob) 
#Printing the number of Bobs

Or with the comments preceding the line of code. e.g

numBob = 0
s = 'sexbobombob'
#Generates a list from 0 to the length of s
i = range(len(s)+1)
# This would be the variable storing each value of the list
u = 0
# this allows me to extract each value of i
for ans in i:
 # Completely arbitrary. i just used any condition that allows me to pick up all values in the list.
 if ans > 0:
 u = ans
 # By using indexing to pick u, u+1, and u +2 i can pick up 3 letters at a time
 x = s[u:u+3]
 # Checking if the term i picked up is a Bob
 if "bob" in x:
 # increasing the Bob count
 numBob += 1
 # Printing the number of Bobs
print "Number of times bob occurs is:" + str(numBob) 

• janos: It's recommended to follow the style guide: python.org/dev/peps/pep-0008

Answer 1

Using this kind of all-top-level short-named fully imperative style forces you to rely heavily on comments to make the code readable.

Comments everywhere repeating the code violate the DRY principle:

 # increasing the Bob count
 numBob += 1

You just doubled reading / maintaining time here.

Descriptive names, examples of usage and sometimes functional style make "how"-kind comments unnecessary:

def count(substring, string):
 """
 >>> count("bob","bobhejrhaabobfqbqsanbobb")
 3
 """
 return sum(substring == group for group in groups(string, len(substring)))
def groups(xs, n):
 """
 >>> groups([1, 2, 3, 4, 5], 3)
 [[1, 2, 3], [2, 3, 4], [3, 4, 5]]
 """
 for i in range(len(xs)-n):
 yield xs[i:i+n]

The code looks self explaining to me, but feel free to ask about any doubts about it.

• 200_success: Even simpler: def count(substring, string): return sum(string.startswith(substring, i) for i in range(len(string) - len(substring)))